Nonsmudging transfer sheet



March 9, 1954 CCCCCCCCC UM 2.671,734

INVENTOR. CARL kaz/yet. (IM

Patente Mar. 9, 1954 TATES PATENT OFFICE &671,734

NDNSMUBGG TRANSFER SHEET Application March 25, 1949, Serial No. 83,347

(Cl. :il'i-36) 3 Claims.,

My present invention relates generally to manifolding, and has particular reference to transfer sheets or media adapted for use with a pressure or impact instrumentality such as a pencil or the keys of a typewriter. Examples of such media are ordinary carbon paper, typewriter ribbons, so-called hectograph or Spirit carbon paper. and the like. In each case there is a base upon Which there is an adherent coat ing of a pigmented or dye-carrying marking material adapted to transfer itself onto a contacting surface in response to concentrated impact or pressure.

The tendency of such sheets or media to smudge the surfaces With Which they come in contact, including the fingers of the user, has long been recognized, and it is a well-known expedient to apply a protectve film to the layer of marking material in order to overcome this.

'The film is composed essentially of a waxy, resinous, or equivalent substance which is applied in liquid state (by use of a solvent, for example, or by liquefying the substance). It is adapted to form a very thin film which is flexible but which readily ruptures under the impact or pressure to which the underlying layer of markihg material is subjected When in use.

The composition of the protective film is of course so chosen that it will be unreactive toward the material Which it covers. Nevertheless. it has been found in practice that despite all precautions there is usually some degree of undesirable chemical action (especially during the process of application of the film) between One or more of the ingredients of the underlying layer and one or more of the ingredients (or solvents, if used) of the film. Moreover, and quite apart from any such chemical interaction, there is always a deleterious mingling of the two contacting layers, caused by diffusion, Which impairs the qualities of the product. For example, the diffusion of the material of the protective film into the underlying layer may undesirably afiect the brilliance of the dye used (in the case of hectograph carbon paper), or may undesirably affect the opacity or other attributes of the marking material. Conversely, the diffusion of the dye or pigment into the overlying film may not only impair the apcearance of the latter but may so diminish its eiicacy that the protective film itself becomes a source of the very smudging it is intended to prevent.

It is an object of the present invention to obviate these disadvantages, and to provide a transfer medium of 'the character referred to 2 which is guarded against smudging, and also against other shortcomings, in a manner which is more effective than any of those heretofore employed in practice.

The invention is predicated upon the discovery that the so-called leafing' properties of certain powdered materials, notably bronze powders, can be utilized to good advantage in the manuacture of a transfer sheet or medium of the character mentioned. The materials I refer to have powder particles in the form of fiakes. When such powders are suspended in a liquid medium they tend to concentrate at the surface of the liquid and to Orient themselves with the fiat dimensions of the flakes parallel to the surace, thus 'producing what appears to be a continuous layer or skin. It is this phenomenon which is known as "leangf' By suitably incorporating such a powdered material as a minor ingredient in the film which is applied in liquid form to the transfer composition of a manifolding sheet, a number of advantages are achieved. The powdered material leafs not only at the outer surface of the film, but also at the interface between the film and the underlying composition which it is intended to protect. Accordingly, layers or skins are produced which not Only protect the film from the atmosphere but which eiectively separate the film from the composition beneath it. These skins are extremely thin, they are flexible, they readily rupture along with the film itself, and for these reasons they do not aiect the efficiency of the transfer medium when it is used. The skin at the interface minimizes chemical interaction during the application of the protective film, and serves as a complete barrier to any subsequent diffusion between the layers. The skin at the outer surface guards the protective film itself from the effects of air, moisture, chemicals. Or handling. And if an opaq'ue powder is used, both skins serve as a light barrier as well, thereby preventing impairment of the marking material by actinic rays. Moreover, by a selection of the powdered material to be used, or by suitably intermixing Such powders, various colors may be imparted to the coated side of the transfer sheet.

The leafing materials Which I prefer to employ are those known as bronze powders. This term includes within its scope a variety of different metal powders such as aluminum, Copper, Copper-base alloys,` gold, lead, nickel, silver, or tin. Any of these bronze powders, or selected mixtures of them, may be used in the practice 3 of the present invention, and this is the significance intended to be applied to the term "bronze' powder" as used hereinafter and in the appended claims.

In the accompanying drawing, the figure is an enlarged Cross-section of an illustrative transfer-medium showing the present improved coatings thereon.

The layer lu may be considered to be any selfsustaining base of sheet-like character, such as a piece of suitable carbonizing tissue. Such tissue may, for example, have a thickness of approximately .0025 inch. Adherent to the base is a coating H which may be a marking material of any usual character or composition, adapted to transfer itself under concentrated pressure Or impact to a surface held in contact with the transfer Sheet in the usual and wellknown way. By way of example, the composition ll may be approximately .001 inch thick.

To prevent smudging, the layer ll is covered by a protective coating or film [2. This coating is composed essentially of a substance adapted to form a thin protective film which is flexible but readily ruptured under the concentrated pressure or impact to which the transfer sheet is subjected when in use. The film Iz is preferably applied by means of an applicator roll and doctor blade so that its final thickness does not exceed approximately .0005 inoh; but any Suitable spraying or brushing procedure may be used, if desired. It is the protective film l2 with which the leafing material of the present inventionis incorporated, to form concentrated areas or skins l: (at the outer surface) and ll (at the interface). Each of these skins is composed of oriented overlapping fiakes of the powdered material.

It will be understood that the invention is applicable to any transfer sheet or transfer medium of known character, and that the material of which the base lo is composed, and the composi' tion or mode of application of the marking material Il may be of any suitable or desired kind. Similarly, the procedure by means of which the protective film I2 is applied to the coating ll forms no part of the present invention. It is the composition of the protective film l2 to which the benefits of the present invention are directly attributable. The following examples are there- :fir-e directed to the formulation of the protective The wax is melted at about 170 F., and the powder is then added, and the mixture is stirred until the powder is dispersed. The composition may then be sprayed, brushed, or otherwise applied to the transfer sheet, to form a protective film of the character hereinbefore described.

Beeswax is illustrative of those waxes which usually have suicient inherent adhesive quality to make the protective film adhere to the surface to which it is applied. Other waxes that could be used, in place of the beeswax in the foregoing example. are microcrystalline wax, Japan wax, a low-melting-point pitch, or either of the products made by Glyco Products CO. Inc., New York, N. Y.. known as "Fiexo wax" and "Adhesio wax,"

o Emmpla II Percent The paramn in this example is illustrative of those waxes which are deflcient in tackiness, and which therefore benefit from the addition of a small percentage of a tackifier, such as rosin.

Other waxes that couldbe used in place of the parafiln in this formula are ceresine wax, Chinese insect wax, spermaceti, or a chlorinated paramn wax made by Halowax Corporation, known as Halowax." A product known as "Carbowax," consisting essentially of poly-ethylene-glycol and made by Carbide & Carbon Chemical Corporration, may also be used where the composition tobe covered by the protective mm does not include any aniline dyes.

As a substitute for rosin. any other suitable tackifler might be employed, such as cumar resin, para rubber, poly-isobutylene, chlorinated dlphenyls, or lanolin.

Example III Percent Candelilla wax Petrolatum 5 Bronze. powder 5 The petrolatum in this formula serves as a plasticizer. In its place, there may be used any other well-knownv plasticizer which is miscible with wax, such as mineral oil, lard oil, sperm oil, lanolin, or a low-melting-point paramn.

The candelilla wax is illustrative of those waxes which benefit from the addition of a plasticizing agent. Other waxes of this general kind, which could be used in this example in place of the candelilla wax are Esparto wax. ouri-curi wax, Montan wax. Utah wax, or sugar cane wax.

In this formula, the paraffln serves as plasticizer, and the rosin as a tackifier.

In each of Examples II, III, and IV. the decision as to whether a tackifler or plasticizer should be used, Or both, will depend upon the nature of the wax which is chosen as the main ingredient of the composition, and upon the adhesiveness and liquidity desired. All of the waxes are more or less interchangeable, so far as the general objective of the invention is concerned. and they can be used singly or in various combinations, the viscosity and tackiness in each case being modified, if desired, in the manner indicated.

In all of the foregoing examples. the essential ingredient of the composition is a substance which is liquiflable by heat. The film is therefore applied by first melting the ingredients. then applying the composition, and finally allowing it to cool.

The invention is not restricted, however. to this procedure, and the following example is 11- lustrative of the way in which the film may be v produced by first dissolving the ingredient in a suitable solvent, and subsequently allowing the solvent to evaporate.

In this example, the ethyl cellulose is a resin which is adapted to form a protective film of the desired characteristics. The phosphate and the stearate are plasticizers. Equivalent resins and plasticizers may be substituted, if desired.

The solid ingredients are in this case dissolved in a suitable solvent, such as ethyl acetate, using about ,10 parts of Solids to each 90 parts of solvent. After suitable stirring, to disperse the bronze powder, the composition may be applied to the transfer sheet at room temperature, and after the solvent has evaporated, a protective film of the present character remains on the transfer sheet.

It has been found preferable to use the leafing material in an amount between 05% and 10.0% of the film composition. In each of the examples given, therefore, it will be understood that the percentage of leafing material may be varied within these limits, and that the main filmforming ingredient will be increased or decreased accordingly.

wherever desired, additional pigments or fillers may be used in the protective film, to aifect its opacity, its color or appearance, or its odor, as may be desired.

In general, it will be understood that the details herein described and specified may be varied in a number of respects, without necessarily departing from the Spirit and scope of the invention as expressed in the appended Claims.

Having thus described by invention and illustrated its use, what I claim as new and desire to secure by Letters Patent is:

1. In a transfer sheet comprising a base and a layer of marking material thereon: a protective anti-smudge coating overlying said layer and composed essentially of a substance adapted to form a film which is flexiblebut readily ruptured under concentrated impact or pressure, said coating including along its outer surface an extremely thin flexible readily rupturable protective skin of leafed bronze powder and including also, along the interface between said coating and the underlying layer of marking material, a second thin flexible readily rupturable skin of leafed bronze powder which is a barrier against chemical interaction and diifusion between said coating and said underlying layer.

2. The protective anti-smudge coating defined in claim 1, in which the bronze powder forming said skins constitutes 0.5 to 10.0% of said coating.

3. A pressure sensitive hectograph transfer member comprising a flexible base sheet; a layer of marking material thereon including hectographic proportions of Spirit soluble dye therein; and a protective anti-smudge covering overlying said layer, and including essentially leafed bronze powder particles and a substance forming a flexible film in which Said particles are embedded, said leafed bronze powder particles protecting said marking material against inadvertent scutfing and preventing dye migration through said film, said film being adhesively attached to the marking layer and frangible under inscribing impact or pressure to transfer portions thereof with underlying portions of the marking layer to a copy sheet and being adhesive to attach such transferred portions to the copy sheet.

` CARL ROSENBLUM.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,864,097 sherman June 21, 1932 1,954,450 Lawrence Apr. 10, 1934 2,213,645 Antrim Sept. 3, 1940 2,322,367 Kjellstrand June 22, 1943 FOREIGN PATENTS Number Country Date 856,878 France Aug. 13, 1940 

1. IN A TRANSFER SHEET COMPRISING A BASE AND A LAYER OF MARKING MATERIAL THERON: A PROTECTIVE ANTI-SMUDGE COATING OVERLYING SAID LAYER AND COMPOSED ESSENTIALLY OF A SUBSTANCE ADAPTED TO FORM A FLIM WHICH IS FELEXIBLE BUT RADILY RUPTURED UNDER CONCENTRATED IMPACT OR PRESSURE, SAID COATING INCLUDING ALONG ITS OUTER SURFACE AND EXTREMELY THIN FLEXIBLE READILY RUPTURABLY PROTECTIVE SKIN OF LEAFED BRONZE POWDER AND INCLUDING ALSO, ALONG THE INTERFACE BETWEEN SAID COATING AND THE UNDERLYING LAYER OF MARKING MATERIAL, A SECOND THIN FLEXIBLE READILY RUPTURABLE SKIN OF LEAFED BRONZE POWDER WHICH IS A BARRIER AGAINST CHEMICAL INTERACTION AND DIFFUSION BETWEEN SAID COATING AND SAID UNDERLYING LAYER. 